   function s1_read_last_two_bytes_of_a_mbr_backup_file(){
	   local file_path=$1
	   local last_bytes=$(tail -c 2 "$file_path" | od -A n -t x1 | tr -d ' \n')
	   if [ "$last_bytes" = "55aa" ];then
		   echo "YES"
	   else
		   echo "NO"
	   fi
   }
   function s2_read_mbr_partition_table_info(){
	   for i in {0..3};do
		   offset=$((446 + i * 16))
		   start_sector=$(dd if="$1" bs=1 skip=$((offset + 8)) count=4 2>/dev/null | od -t u4 -An | tr -d ' \n')
		   if ! [[ $start_sector =~ ^[0-9]+$ ]];then
			   continue
		   fi
		   if [ "$start_sector" -eq 0 ];then
			   continue
		   fi
		   size_sector=$(dd if="$1" bs=1 skip=$((offset + 12)) count=4 2>/dev/null | od -t u4 -An | tr -d ' \n')
		   end_sector=$((start_sector + size_sector - 1))
		   echo "$start_sector $end_sector"
	   done
   }
   function s3_parse_partition_info(){
	   fdisk_output=$(cat)
	   dsik_size_bytes=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $5}')
	   dsik_size_sectors=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $7}')
	   physical_sector_size=$(echo "$fdisk_output" | grep "Sector size" | awk '{print $4}')
	   first_partition_seart_sector=$(echo "$fdisk_output" | grep "dev/vda1" | awk '{print $3}')
	   first_partition_end_sector=$(echo "$fdisk_output" | grep "dev/vda1" | awk '{print $4}')
	   first_partition_type=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{ptint $8}')
	   echo "disk size in bytes:$disk_size_bytes"
	   echo "disk size in sectors:$disk_size_sectors"
	   echo "physical sector size in bytes:$physical_sector_size"
	   echo "first partition start sector id:$first_partition_start_sector"
	   echo "first partition end sector id:$first_partition_end_sector"
	   echo "first partition type:$first_partition_type"
   }
   function s4_run_passwd_as_plain_user_and_get_status(){
	   oversleeping_path=$(which oversleeping)
	   chown root "$oversleeping_path"
	   chmod 755 "$oversleeping_path"
	   $oversleeping_path &
	   ps -o uid,euid,ruid -C 'oversleeping' | awk 'NR>1 {print $1","$2","$3}'
   }
   function s5_add_a_scheduled_task(){
	   (crontab -l 2>/dev/null; echo "*/5 * * * * echo \$(date +'\%Y\%m\%d_\%H\%M\%S') >> \$HOME/test_crontab") | crontab - 
   }

